Recent Advances in Analytical and Field-Deployable Methods for Detecting Substandard and Falsified Pharmaceuticals

Substandard and falsified medical products remain a persistent threat to public health, with the heaviest burden falling on low- and middle-income countries that have limited regulatory and laboratory capacity. Detecting poor quality medicines is intrinsically difficult because no single technique captures the full range of defects, which span absent, incorrect, degraded or subtherapeutic active ingredients as well as deliberately deceptive packaging. Over the past decade a two-tier surveillance model has consolidated around inexpensive, portable screening at or near the point of sale, followed by confirmatory analysis in reference laboratories. This paper reviews recent progress across that continuum. It outlines the epidemiology and public health burden of poor quality medicines, the sampling and survey design that underpins credible surveillance, and the confirmatory chromatographic and mass spectrometric methods that serve as the analytical reference. It then examines field-deployable vibrational spectroscopy in the near-infrared, Raman and mid-infrared ranges; additional structural methods including benchtop nuclear magnetic resonance, terahertz spectroscopy and X-ray techniques; low-cost chemical and paper-based tools such as thin-layer chromatography kits, paper analytical devices and electrochemical and microfluidic platforms; emerging portable and ambient ionisation mass spectrometry; and the rapid expansion of digital approaches including smartphone image analysis, chemometric and machine learning models, cloud-connected spectral libraries, and product authentication and track-and-trace systems. The techniques are compared against criteria that matter in resource-limited settings, namely sensitivity, specificity, cost, portability, training burden, destructiveness and throughput. The central argument is that the most credible path forward is not a single breakthrough device but the intelligent integration of complementary methods, supported by shared reference databases, harmonised validation protocols and sustainable financing. Persistent gaps in library availability, quantification of active ingredient content, data governance and programme sustainability are identified as priorities for future work.